Design and implementation of a novel differential mode active EMI filter with a twin circuit

A novel active EMI filter for differential mode noise attenuation is proposed. The filter consists of a twin circuit that is made up of low voltage/current components that mimic the high power components in the main circuit. The twin circuit uses a constant impedance to represent the mains impedance. Compensation networks to improve stability could be added to the low voltage circuitry thus avoiding any additional high voltage components. The modeling of the entire circuit is carried out and the design example is presented. The experimental results show 22 dB attenuation around 150 kHz using the proposed filter.